door threshold cavity

[Callismichael]

Morning all

I'm currently lining my door threshold with a dpm and filling with concrete. I've dug out all the rubble but I'm now left with damp earth. I'm about 4 brick depths down.

Do I start the dpm at this level or carry on removing the soil? Seems very deep and difficult to remove the earth as it's well compacted but is damp.

Regards
Michael

 

[Blagard]

Assuming that this is for an older house stop there.

The concrete should fill to the outside gound level ideally with the concrete at the top sloped towards the outside with some weep holes in the perps to allow any water that gets into the cavity to run out. Just look up the images on the internet it is a standard detail. The above ground part of the cavity should be clear up to DPC level and the threshold level closed off with a DPC. If the inside floors of a house are below external ground levels please advise as the detailing would be different.

 

[Callismichael]

Thank you very much for the reply.

It's an early 1980's property. The inside floor is above ground level. If I need sloping concrete how would I do this as I need to fill to floor level so flooring can go down? I'm going to insert perimeter insulation aswell.

 

[Blagard]

To get a slope on cavity fill just put a splay cut on the end of a batten that you use to "tamp" the top of the concrete.

There are many ways to close off the top of a cavity. One way would be to remove the inner course of brickwork around 75 to100 below floor level then get some tiles or slates to bed onto the lower course to bridge the cavity, these will act as permanent formwork to support a layer of concrete to finish flush with the existing floor structure Your DPM should be extended across the tiles and up the side of the outer leaf before you concrete. Trim off the excess afer doing the concrete. If the DPC to the inner leaf is below the course of bricks removed you should be OK to just have a DPC on the inner face of the external leaf. If you are lucky with the brick course heights you might even be able to use a proprietory cavity closer.

In situations where the threashold has been created by extending a window opening down or some other new opening sometimes the height of the external leaf of brickwork does not marry up with your floor levels and if too late to adjust then you may find dressing the exposed edge of brick with a PVC angle or other material complimentary to the frame that sits on it.

As for the cavity above ground level and below your threashold treat that the same way as the rest of the house is constructed

 

[Callismichael]

Thank you very much for the reply. So at the moment because the void is about 4 brick courses deep should I refill with the soil up to almost outside ground level then create a slope with a batten, then lay dpm and fill. What's confusing me is the slope will be covered with dpm and concrete so technically it's bonded so rain aater would sort of be trapped as here would be no gap for it to travel outdoors?

Sorry for all the questions just don't want and trapped damp.

Some people say to create a dpm trough but I don't know if it should go so deep under ground where I could be creating more issues.

Also there's nothing to rest slate on due to the sill being in line with outer brickwork. Inner course is a solid concrete slab aswell so can't remove.

 

[Callismichael]

 

[Blagard]

Read again what I wrote.

If the inner leaf of bricks is against a solid floor that does not stop you taking those bricks out! I don't see the concrete extending over the inner leaf as it looks to me like bricks in your photo.

The tile or slate I described sits on the inner leaf one brick down and cantilevers over the cavity. The DPC and concrete is on top of that bringing the level back up but closing the cavity at the same time.
Essentially you replace the inner course of bricks with concrete that is wider.

Depending on what is going on your floor I would consider a commercial cavity closer to make it easier than messing around with concrete.

What is that chipboard doing in your photo?

Edit:
Just looked at some of your earlier posts and without reading any detail it seems Noseall has already been through it with you to describe a way to deal with threasholds. It may not be exactly the same but the principle probably is - Physically close off the top of the cavity whilst extending the DPM/DPC as necessary to protect the structure from dampness.

 

[Callismichael]

Hi thanks for the reply. The problem is it's a slab floor so no bricks to remove and dpm where inner bricks sat on top of slab so only way to do it would be chisel the slab down but then I can't fit a closer. Sorry to trouble you. Seen nosealls reply. So would it be ok to just rest the slate on the slab and float over the cavity and not rest on brick below sill? If so then I would only be able to get about 2cm screed on top of the tiles. And I would also need an upstanding of insulation.



Chipboard is just covering a water pipe hole that needs filling

 

[Callismichael]

ok so all sorted. plan is to fill cavity up to the height of xternal ground level, DPM and screed to floor level. BC were happy with this method. Just thought i'd update as there are several ways to do this but thought I would share in case others have, like me mulled over this for a considerable amount of time. Thank you for your advice and time. Great forum.

 

[Blagard]

Ah! so what looked like a row of bricks in the photo was in fact a DPC on top of the slab! - From what you describe you have elected to line the cavity with a DPM material above the concrete cavity fill and then to fill that lining (which is like a large bag) with a screed material. That is an unusual way I have not come across before.

 

[Callismichael]

yea so fill up with concrete up to outside ground level, DPM into the void 2 brick courses down lapping up the door and fill with screed to FFL.